Beat eggs until light. Gradually add sugar, continue beating until mixture is thick and sugar completely dissolved. Sift dry ingredients several times. Melt butter in hot water. Sift dry ingredients over egg mixture, fold in lightly; then, working quickly, fold in hot-water-and-butter. Pour into lightly greased 18 cm x 28 cm lamington tin. Bake at 180°C for approximately 30 minutes.